Effects of selective attention on the peripheral auditory system: Otoacoustic emission assays of cochlear function during behavior

University of Minnesota Ph.D. dissertation. March 2019. Major: Psychology. Advisors: Andrew Oxenham, Magdalena Wojtczak. 1 computer file (PDF); xix, iv, 146 pages.Selective attention is an important ability that humans use to navigate a crowded sensory world. In audition, attending to a target while ignoring distractors results in an enhancement of the neural representation of the target and an attenuation of distractors. The neural underpinnings as well as the location of this process within the auditory pathway is not clear. This thesis explores the possibility that the medial olivocochlear reflex, an auditory efferent neural circuit, might aid in selective attention by modulating the gain produced by the cochlea during selective attention. Otoacoustic emissions, small sounds originating in the cochlea, are used to measure changes in cochlear function while participants perform tasks that require attention to either only auditory or only visual stimuli. Experiments assess the replicability of otoacoustic measures made during selective attention, the effect of the perceptual load of attention tasks on these otoacoustic measures, and whether the effects of attention differ with respect to location within the cochlea. Across five experiments results consistently show no evidence for changes in cochlear function during selective attention to auditory or visual stimuli. The results challenge much of the existing literature, which reports small but significant effects of attention, but often in conflicting directions across studies. The results highlight significant variability between individuals in otoacoustic measures of cochlear function, which remains to be explained